ECT Sensor with Unique Structure for Robot Gripper Application

Electrical capacitance tomography (ECT) is a powerful tool for imaging the internal permittivity distribution in industrial processes. For applications of ECT with robotic fingers or grippers, it is necessary to consider how to place ECT electrodes on robotic fingers. In this paper, a three-finger symmetrical gripper is used with four electrodes on each finger. The impact of the gap between adjacent electrode groups on image reconstruction is investigated. With the different ratio of the inter-group gaps to the inter-electrode gap, ranging from 1:1 to 25:1, the capacitance of all electrode combinations is obtained by simulation. Image reconstruction is conducted using linear back projection (LBP) and Landweber iteration, with weighted electrode pairs and multi-angle fusion, followed by optimization. For stratified targets, multi-angle fusion and optimized fusion achieved high correlation coefficients across all gap ratios (exceeding 0.9 and 0.77, respectively). For two-object targets, only optimized fusion maintained correlation coefficients above 0.8 within the range of gap ratio from 2:1 to 14:1. These findings demonstrate that optimized gap ratios and weighted pairs can ensure ECT imaging quality.